In butt fusing machines in use heretofore, clamps, one of which is movable relative to the other, grip ends of two pipe sections to be fused. A facer is placed between the two pipe ends, and the ends of the pipe faced off in substantial parallelism. The facer is removed, and a heater is placed intermediate the butt ends of the sections and the butt ends are brought into contact with the heater by means of the movable clamp, until the end surfaces are softened, the sections are pulled apart slightly, the heater removed, and the softened ends brought together by the action of the movable clamp. The basic process is illustrated in U.S. Pat. Nos. 3,013,925 and 3,552,265, in which the steps of moving the pipe sections and inserting and removing facer and heater are performed manually. Machines are presently in use in which those steps are performed hydraulically, cf. Manufacturing, Inc. Bulletin No. 5761.
The clamps have been made up of semi-cylindrical shell members which have most commonly been oriented so that the pipe-receiving mouth of the lower shell is substantially horizontal, although canted shells, in which the mouth is set at an angle from the horizontal, have been known.
One of the objects of this invention is to provide a butt fusion machine, particularly useful for large diameter plastic pipe, in which the steps of facing, heating and butting of the pipe and lining of the shells are all simplified and faster as compared with the steps required in butt fusion machines used heretofore.
Another object is to provide such a machine in which provision is made for minimizing the sensitivity of the hydraulic valve setting when the pipe is butted for fusing.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.